Intra-abdominal desmoid tumor mimicking locoregional recurrence after colectomy in a patient with sporadic colon cancer: report of a case.

Desmoid tumors are rare, benign fibromatous lesions that result from the abnormal proliferation of myofibroblasts. A 61-year-old man underwent laparoscopy-assisted right hemicolectomy for ascending colon cancer. The final TNM stage was stage IIIB (T3N1M0). Follow-up computed tomography (CT), done 12 months after primary surgery, showed a nodular, enhancing soft-tissue density mass, 12 mm in size, in the mesentery, near the anastomosis. Another CT scan, done 4 months later, revealed that the tumor had enlarged to 27 mm in size. We suspected locoregional recurrence of colon cancer and resected the tumor, together with the distal ileum and colon, including the previous anastomotic site. The tumor was histologically diagnosed as a desmoid tumor. The patient remains well 24 months after his last operation. Differentiating between the desmoid tumor and locoregional recurrent tumor was difficult, and surgical resection was the optimal treatment.